Question

calculati numarul de molecule de apa dintr-un pahar de 250 grame​

Answer 1

Răspuns:

MH2O =2×1+16=18g/mol

1mol H2O...........18g H2O........6,023×10²³molecule

250g H2O.........x molecule

x=250×6,023×10²³/18= calculează

Answer 2

$M_{H_2O}=1 \cdot 2+16 \cdot 1=2+16=18 \ g/mol \\ m_{H_2O}=250 \ g \\ n_A=6,02 \cdot 10^{23} \ molecule/mol \\ \nu=\frac{m}{M}=\frac{n}{n_A} \\ \Rightarrow n=\frac{m \cdot n_A}{M}=\frac{250 \ g \cdot 6,02 \cdot 10^{23} \ molecule/mol}{18 \ g/mol} \\ \Rightarrow \boxed{n=8,36 \cdot 10^{24} \ molecule}$